1. Field of the Invention
The present invention relates to dental prosthesis and, in particular, dental implant prosthesis and an apparatus and method for making same which removably secures the artificial teeth portion to the underlying support of a partial or full dental prosthesis.
2. Description of the Prior Art
In the area of dental prosthetics, there have been primarily two major types of dental implant prosthetics which have been in use. The first, commonly known as the overdenture, provides for support structure to be implanted in the alveolar bone, which support structure extends above the gum line and permits the patient to snap-fit the denture in place. This type of construction permits the patient to remove the denture himself and clean the denture and gum area. The drawback of an overdenture is that it does not normally provide sufficient stability under all eating or chewing conditions.
The second type of prosthesis in wide use is that of the fixed prosthesis. Again, a support structure is anchored in the alveoloar bone, the support structure extending above the gun line and the prosthesis being permanently secured through the support structure into the bone. This type of denture normally provides a more stable denture for the patient, but aesthetic and hygiene problems arise in that the denture can only be removed by a dentist to permit cleaning in the area under the prosthesis and proximate to the support structure.
Applicant, in his prior patent, U.S. Pat. No. 4,931,016 disclosed an apparatus and method for making a fixed, removable dental prosthesis which the individual could remove for cleaning of the prosthesis and the underlying gum area. The prosthesis disclosed in the aforementioned patent provided the necessary stability for all eating and chewing conditions, but allowed the individual to remove the prosthesis for cleaning thereby eliminating the need for a dental visit.
Applicant has further refined the aforesaid dental implant system with the development of a novel latching attachment which secures the supra structure of the prosthesis which contains the secondary support bar and artificial teeth, to the underlying primary support bar. This novel latching attachment provides for greater strength in the attachment process and further secures the stability of the prosthesis under all eating and chewing conditions.
The secondary support bar and the primary support bar are fitted together in accordance with the teachings of Applicant's aforesaid U.S. Pat. No. 4,921,016. A latching mechanism is normally provided on the interior rear portion of the prosthesis to allow the user to remove the secondary support bar and overlying artificial teeth for cleaning as well as to permit cleaning of the gum area about the primary support bar. The usual manner of preparing the latch was to form an opening perpendicular to the PG,4 primary and secondary support bars, in a horizontal axis and to then fit a rotatable clip in the aperture which could be twisted to a locked position to an unlocked position thereby allowing the removal of the secondary support bar and overlying prosthesis. These twist-lock clips secure the denture in two places in the rear of the mouth. The secondary support bar had sufficient downwardly depending detentes, cooperative with apertures in the primary support bar to prevent the secondary support bar and overlying prosthesis from moving in a horizontal plane with respect to the primary support bar. However, a significant amount of stress is placed on the prosthesis during the eating process, which stress attempts to vertically separate the secondary support bar and overlying denture or prosthesis from the primary support bar. The aforementioned twist-lock clips were the sole means for preventing this vertical separation with the exception of the frictional engagement between the secondary support bar and the primary support bar.
Certain of the problems associated with the twist-lock clip were inherent in the sparking erosion of their receptacle through the electrical discharge method.
In spark eroding the aperture for the securing mechanism, the electrode can cause three basic problems which do not permit the tight fit of a securing means. The first undesirable property is that of overcut. This is the tendency of the electrode to erode or cut an aperture slightly larger than itself. This occurs because of previously eroded material passing along the sides of the electrode for removal and causing additional erosion to the work piece as they pass.
The second undesirable property is taper caused by the same particles or residue being flushed from the bottom of the eroded hole. These particles continue to create discharge as they pass along the surfaces causing more metal to be removed in these areas. Flushing or suction is utilized to minimize this property, but it nevertheless exists.
The third property is the inability to obtain squared corners at the butt end of recesses. This is caused by a higher concentration of flux or discharges at the corner edge of the electrode, thus causing a rounded corner or edge at the butt end of the recess.
These three factors contribute to the difficulty in obtaining a tight, secure fit for the securing mechanism for the dental prosthesis. They contribute to the introduction of a slight play in the twist-lock clip which over time may cause wear and a looseness in the fitting between the secondary and primary bar. While the twist-lock clip could easily be replaced in this occurrence, the Applicant has developed a clip and a method for fitting it to the primary and secondary bar which provides greater contact area with the primary bar and the method of fabricating same eliminates or greatly reduces the three common problems associated with sparking erosion which contributes to a much tighter and secure latching mechanism, but one which is easily releasable by the user.